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Abstract
This discovery could open up previously unheard-of market opportunities for GTL liquids, as most refiners think of GTL diesel rather than GTL naphtha as a potential ultra-clean diesel fuel blendstock. Most petrochemical makers think of GTL naphtha as a superior ethylene cracker feedstock. But new tests show GTL naphtha could enjoy a wider market in fuels. GTL diesel is indeed a superior blendstock to GTL naphtha because of GTL diesel's very high natural cetane (over 70), near-zero sulfur/aromatics, high hydrogen/carbon ratio, and good low- temperature properties when isomerized.
Sasol made its discoveries about FT naphtha when testing blends of ordinary petroleum diesel and FT naphtha at its test facilities at Sasolburg, using a 206Kw heavy-duty Mercedes-Benz 407T diesel engine. Sasol's Slurry Phase Distillate (SPD) technology - as proposed for plants in Nigeria and Qatar - would yield roughly 70% diesel range products and about 30% FT naphtha. While the straight-run FT naphtha is a high-quality steam cracker stock for ethylene production, some of the straight-run products could be hydrogenated or hydrocracked, or partially blended with SPD diesel, to produce an acceptable diesel blendstock, Sasol's Principal Process Engineer Luis Dancuart showed at the National Petrochemical & Refiners Association annual meeting here.
Because of these encouraging results, Sasol next tested SPD naphtha blends in petroleum diesel. Following are fuel characteristics, fuel consumption and emissions data comparing pure SPD naphtha, 50% SPD/petroleum diesel blend, and on-road South African Diesel (summer grade). Sasol also compared the quality of the FT naphtha and naphtha/diesel blends with Canadian petroleum diesel fuels specifications to determine the practicality of such blends in cold North American climates: